Tetraamelia

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The preacher Nick Vujicic has no limbs except for the remains of a foot and toe on the base of the left thigh

Tetraamelia (from the Greek tetra 'four' - 'without limbs') describes a very rare malformation ( amelia ) of the four limbs. The cause is an autosomal - recessive inherited genetic defect.

pathology

Tetraamelia often occurs in various parts of the body, including the head, heart, nervous system, skeleton, and genitals, along with other serious malformations. In many cases, the lungs are not fully developed, which makes breathing difficult or impossible for those affected. Because affected children suffer from such serious health problems, many are stillborn or die shortly after birth.

Molecular biology

The cause of a tetra amelia is a mutation- induced defect in the WNT3 gene. This gene is part of the group of WNT genes that play a critical role in prenatal development. In humans, the WNT3 gene is located on chromosome 17 locus q21. This defect is inherited as an autosomal recessive trait. The parents of children with tetra-amelia each carry a mutated gene, but do not show any phenotypic expression.

Epidemiology

The protein produced by WNT3 is involved in the formation of limbs and other body structures during embryonic development. Mutations in the WNT3 gene prevent the cells from producing functional WNT3, which disrupts the normal formation of the limbs and leads to other serious birth defects associated with tetra-amelia.

Demarcation

While tetra-amelia is a separate syndrome, tetraphocomelia is a phenotypic expression in various syndromes, such as Roberts syndrome .

literature

Individual evidence

  1. ↑ Regine Witkowski, Otto Prokop, Eva Ullrich, Gundula Thiel: Lexicon of Syndromes and Malformations: Causes, Genetics and Risks . Springer, 2003, ISBN 3-540-44305-3 , pp. 1059 ( limited preview in Google Book search).
  2. ↑ Tetraamelia.  In: Online Mendelian Inheritance in Man . (English)